The invention relates to a protective device for an iron.
Irons are usually used for ironing clothing. Problems appear regularly with the use of irons as soon as the risk of overheating arises. This overheating can occur on the one hand as soon as the iron standing on the iron surface is forgotten about by the user or, as a result of carelessness, when an object such as an item about to be ironed is thrown over the iron surface or falls thereon by chance.
A protective device for irons is disclosed in JP 4-114699 A in which a contact switch is provided on the base of the iron. The switch maintains the current supply if the iron is placed on its end. If the iron is guided over an object by its iron surfaced, a further light-sensitive sensor establishes that the iron is abutting against a surface to be ironed and in principle interrupts the current supply to the heating surface. As a further condition, which is required to maintain the current supply to the heating surface when the light-sensitive sensor is applied to a surface, a device is provided in the handle in order to allow a tracking current upon actuation of the handle by the user. If the logic unit then establishes that a tracking current is flowing and, in parallel, that the light-sensitive sensor is abutting against a surface, further heating of the heating surface is permitted. Therefore, it is not established in JP4-114699 whether the iron is moving or not. Instead, it is merely established within the iron is being actuated by a person. A further problem in JP4-114699 resides in the fact that, when the iron is placed on its end, the heating surface is constantly heated with the result that it would not be possible to ensure that in fact burning would not result if an item of clothing should fall in front of the iron by chance while the user has to answer for example the telephone.
A contact switch is disclosed in DE-G 89 08 132.3 which contains a rolling element that responds to gravity and maintains the current supply as long as the iron is moved in a horizontal position in its position of use. If the iron is placed on its end for example in order to set it aside while the washing is being folded, the contact element rolls into a sustained contact position. However, an undesirable side-effect thereof is that, when sitting on its end, an object can get too close to the heating surface as no check is made of whether an object is situated in front of the heating surface.
In DE 692 06 207 T2 and in the associated European Patent 0 523 793 B1, there is disclosed a textile type sensor which is intended to make possible automatic adjustment of the iron to different types of textiles. In a preferred embodiment, there is provided through a heatable substrate a measuring arrangement for detecting the reflection behavior of the textiles located under the substrate. This measuring arrangement is commonly used and comprises a light emitting diode and a light-sensitive phototransistor. There is no provision for the measured length to be configured with a light diode also as a receiver although this has significant advantages with regard to cost.
Proceeding from the state of the art, the basic object of the invention is to develop an iron in such a manner that an effective, easy-to-integrate protection is produced that ascertains at any time whether there is a risk of overheating of objects abutting against the iron surface and which thereupon switches off the iron.
The invention provides a protective device for an iron having an iron surface and a thermostatically controlled heating device for heating the iron surface. The protective device comprises: a first device for detecting a non-operative state of the iron by being configured to detect a movement and a lack of movement of the iron surface and an object relative to one another thereby generating a first signal; a second device for detecting whether an object is located adjacent the iron surface thereby generating a second signal, wherein the first device and the second device operate in a temporally offset manner and comprise a single system including a transmitter and a receiver for generating the first signal and the second signal; and a logic unit operatively coupled to the single system for receiving the first signal and the second signal therefrom and for interrupting a current supply to the heating device as a function of the first signal and of the second signal when, simultaneously, the first signal indicates a lack of movement of the iron and the second signal indicates an object adjacent the iron surface.
The invention further provides an iron comprising an iron surface; a thermostatically controlled heating device for heating the iron surface; and a protective device. The protective device includes: a first device for detecting a non-operative state of the iron by being configured to detect a movement and a lack of movement of the iron surface and an object relative to one another thereby generating a first signal; a second device for detecting whether an object is located adjacent the iron surface thereby generating a second signal, wherein the first device and the second device operate in a temporally offset manner and comprise a single system including a transmitter and a receiver for generating the first signal and the second signal; and a logic unit operatively coupled to the single system for receiving the first signal and the second signal therefrom and for interrupting a current supply to the heating device as a function of the first signal and of the second signal when, simultaneously, the first signal indicates a lack of movement of the iron and the second signal indicates an object adjacent the iron surface.
The protective device registers the position of the iron and also whether an object is actually situated in front of the iron surface. Two conditions are thereby regularly queried via a logic unit, namely:
a) whether or not the iron is still moving, and
b) whether or not an object is located in front of the iron surface.
According to the present invention, only when the iron is not moving and, simultaneously an object is located near the iron surface, is the current supply interrupted so that damage or even burning cannot result. In all other cases in which it is undesirable for the iron to switch off automatically, the current supply is maintained.
Additionally, according to the present invention, detection of movement and of the object by detectors results via the same transmitters and receivers and via the same measured lengths. The transmitters beam the light which is reflected from the surfaces to be ironed or from an object located above the iron surface. If it is thereby established that the reflection does not change over a specific period of time, both the presence of the object and the lack of movement are established which leads to interruption of the current supply for the heating device.